Blends of poly(vinyl acetal) resins for compositions, layers, and interlayers having enhanced optical properties

ABSTRACT

Resin compositions, layers, and interlayers comprising two or more poly(vinyl acetal) resins and at least one blending agent or haze reducing agent are provided. Such compositions, layers, and interlayers exhibit enhanced optical properties while retaining other properties, such as impact resistance and acoustic performance.

BACKGROUND

1. Field of the Invention

This disclosure relates to polymer resins and, in particular, to polymerresins suitable for use in polymer interlayers, including those utilizedin multiple layer panels.

2. Description of Related Art

Poly(vinyl butyral) (PVB) is often used in the manufacture of polymersheets that can be used as interlayers in multiple layer panels,including, for example, light-transmitting laminates such as safetyglass or polymeric laminates. PVB is also used in photovoltaic solarpanels to encapsulate the panels which are used to generate and supplyelectricity for commercial and residential applications.

The term “safety glass” generally refers to a transparent laminate thatincludes at least one polymer sheet, or interlayer, disposed between twosheets of glass. Safety glass is often used as a transparent barrier inarchitectural and automotive applications, and one of its primaryfunctions is to absorb energy resulting from impact or a blow withoutallowing the object to penetrate the glass. Additionally, even when theapplied force is sufficient to break the glass, the polymeric interlayerhelps keep the glass bonded to the laminate, which prevents dispersionof sharp glass shards, thereby minimizing injury and damage to people orobjects within the interior space. Safety glass may also provide otherbenefits, such as a reduction in ultraviolet (UV) and/or infrared (IR)radiation, and it may also enhance the aesthetic appearance of windowopenings through addition of color, texture, and the like. Additionally,safety glass with desirable acoustic properties has also been produced,which results in quieter internal spaces.

Often, polymers that exhibit one set of desirable properties, such asacoustic performance, lack other desirable properties, such as impactresistance or strength. Therefore, in order to achieve certaincombinations of properties, multilayered polymer interlayers have beenused. These multilayered interlayers may include at least one inner“core” layer sandwiched between two outer “skin” layers. Often, the corelayer of an interlayer may be a softer layer having a lower glasstransition temperature, which enhances its acoustic performance.However, because such resin layers can be difficult to easily processand/or transport, the skin layers of such multilayered interlayers areoften stiffer and have higher glass transition temperatures, whichimparts enhanced processability, strength, and impact resistance to theinterlayer. In some cases, the outer layers may be formed from the lowerglass transition materials, with the inner core layer being the stifferlayer.

At times, use of various resins having different properties can alsoproduce optical defects within the interlayer. For example, one defectcommon to these types of compositions, layers, and interlayers ismottle. Mottle is an objectionable form of optical distortion or visualdefect appearing as uneven spots or texture, usually in the finalstructure. Mottle is caused by small-scale surface variations at theinterfaces between the soft and stiff layers wherein the individuallayers have different refractive indices. Clarity is another importantoptical property that is determined by measuring the level of hazewithin the composition, layer, or interlayer. High haze typically occurswhen different types of optically incompatible polymers and/orplasticizers are blended or mixed together. In such mixtures, lightpassing through the blend is scattered as it encounters regions ofdifferent polymer materials, and the result is a hazy, visually unclearappearance. High clarity polymers and interlayers are those having verylow haze values.

Thus, a need exists for polymer resin compositions, resin layers, andinterlayers formed from blends of poly(vinyl acetal) resins that havedifferent compositions, but that exhibit desirable optical properties.Additionally, such compositions, layers, and interlayers should beproduced without sacrificing mechanical and acoustic performance of thefinal product and should be usable in a wide variety of end useapplications, including as automotive and architectural multiple layerpanels.

SUMMARY

One embodiment of the present invention concerns a mixed resincomposition comprising a first poly(vinyl acetal) resin, a secondpoly(vinyl acetal) resin, and a haze reducing agent. The residualhydroxyl content and/or the residual acetate content of the secondpoly(vinyl acetal) resin is at least 2 weight percent higher or lowerthan the residual hydroxyl content and/or residual acetate content ofthe first poly(vinyl acetal) resin, and the second poly(vinyl acetal)resin is present in the resin composition in an amount of at least 0.3weight percent, based on the total weight of the first and the secondpoly(vinyl acetal) resins. The haze reducing agent has at least onemoiety having a higher affinity for the first poly(vinyl acetal) resinthan for the second poly(vinyl acetal) resin and at least one othermoiety having a higher affinity for the second poly(vinyl acetal) resinthan for the first poly(vinyl acetal) resin, wherein the haze reducingagent is present in the composition in an amount in the range of from0.25 to 20 weight percent, based on the total weight of the composition.

Another embodiment of the present invention concerns an interlayercomprising a resin layer comprising a first poly(vinyl acetal) resin, asecond poly(vinyl acetal) resin, and a haze reducing agent. The secondpoly(vinyl acetal) resin is present in the resin layer in an amount ofat least 0.3 weight percent, based on the combined weight of the firstand the second poly(vinyl acetal) resins; and the resin layer has an HLDhaze value that is at least 5 percent lower than the HLD haze value ofan identical resin layer that does not include the haze reducing agent.

Yet another embodiment of the present invention concerns a method forproducing an interlayer, the method comprising the steps of providing afirst poly(vinyl acetal) resin, a second poly(vinyl acetal) resin, and ahaze reducing agent; and blending the first poly(vinyl acetal) resin,the second poly(vinyl acetal) resin, and the haze reducing agent to forma blended resin composition; and forming an interlayer from the resincomposition, wherein the interlayer has an HLD haze value that is atleast 5 percent lower than the HLD haze value of an identical interlayerthat does not include the haze reducing agent.

DETAILED DESCRIPTION

Resin compositions, layers, and interlayers are provided according tovarious embodiments of the present invention that exhibit improvedoptical properties. In particular, the resin compositions, layers, andinterlayers described herein include at least two poly(vinyl acetal)resins and at least one blending agent or haze reducing agent forimproving the compatibility of typically incompatible resins. Whenblended in the absence of a haze reducing agent or a blending agent asdescribed herein, the poly(vinyl acetal) resins having differentcompositions may provide compositions, layers, and interlayers thatexhibit increased haze and reduced clarity that may be unsuitable formany end use applications, including automotive and architecturalapplications. However, inclusion of blending agents or haze reducingagents as described according to various embodiments herein may resultin compositions, layers, or interlayers having enhanced opticalproperties and that can be used in a wide variety of applications,including multiple layer panels for automotive and/or architecturalapplications.

The present invention generally relates to polymer resin compositions,as well as polymer resin layers and interlayers including the same. Asused herein, the terms “polymer resin composition” and “resincomposition” refer to compositions including two or more polymer resins.Polymer compositions may optionally include other components, such asplasticizers and/or other additives. As used herein, the terms “polymerresin layer” and “resin layer” refer to two or more polymer resins,optionally combined with one or more plasticizers, that have been formedinto a polymeric sheet. Again, resin layers can include additionaladditives, although these are not required. As used herein, the term“interlayer” refers to a single or multiple layer polymer sheet suitablefor use with at least one rigid substrate to form a multiple layerpanel. The terms “single-sheet” interlayer and “monolithic” interlayerrefer to interlayers formed of one single resin sheet, while the terms“multiple layer” and “multilayer” interlayer refer to interlayers havingtwo or more resin sheets coextruded, laminated, or otherwise coupled toone another.

Resin compositions, layers, and interlayers according to variousembodiments of the present invention can include at least two poly(vinylacetal) resins. Poly(vinyl acetal) resins can be formed by acetalizationof poly(vinyl alcohol) with one or more aldehydes in the presence of anacid catalyst. The resulting resin can then be separated, stabilized,and dried according to known methods such as, for example, thosedescribed in U.S. Pat. Nos. 2,282,057 and 2,282,026, as well as “VinylAcetal Polymers,” in the Encyclopedia of Polymer Science & Technology,3^(rd) ed., Volume 8, pages 381-399, by B. E. Wade (2003). The totalamount of residual aldehyde groups, or residues, present in theresulting poly(vinyl acetal) resin can be at least about 50, at leastabout 60, at least about 70, at least about 75, at least about 80, atleast about 85 weight percent, as measured by ASTM D-1396. The totalamount of aldehyde residues in a poly(vinyl acetal) resin can becollectively referred to as the acetal component, with the balance ofthe poly(vinyl acetal) resin comprising residual hydroxyl and residualacetate groups, which will be discussed in further detail below.

In some embodiments, the poly(vinyl acetal) resin can comprise apoly(vinyl n-butyral) (PVB) resin. The acetal component of a poly(vinyln-butyral) resin can include primarily residues of n-butyraldehyde andmay, for example, comprise at least about 50, at least about 60, atleast about 70, at least about 80, at least about 90, at least about 95,at least about 97, or at least about 99 percent of residues ofn-butyraldehyde, based on the total weight of aldehyde residues of theresin. Additionally, a poly(vinyl n-butyral) resin may comprise not morethan about 50, not more than about 40, not more than about 30, not morethan about 20, not more than about 15, not more than about 10, not morethan about 5, not more than about 2, not more than about 1, or not morethan about 0.5 weight percent of residues of an aldehyde other thann-butyraldehyde, based on the total weight of aldehyde residues of thatresin.

One or more poly(vinyl acetal) resins may also include residues of oneor more aldehydes other than n-butyraldehyde. For example, in someembodiments, at least one poly(vinyl acetal) resin in the composition,layer, or interlayer can include residues of at least one other C₄ to C₈aldehyde, including, for example, iso-butyraldehyde,2-methylvaleraldehyde, n-hexyl aldehyde, 2-ethylhexyl aldehyde, n-octylaldehyde, and combinations thereof. In some embodiments, at least onepoly(vinyl acetal) resin may include one or more C₄ to C₈ aldehydesselected from the group consisting of iso-butyraldehyde, 2-ethylhexylaldehyde, and combinations thereof. In various embodiments, at least onepoly(vinyl acetal) resin can include zero weight percent, or can includeat least about 1, at least about 5, at least about 10, at least about20, at least about 30, at least about 40 and/or not more than about 80,not more than about 70, not more than about 60, not more than about 50,not more than about 40 weight percent, or about 0 to about 40, about 0to about 30, about 0 to about 20, about 1 to about 80, about 5 to about70, about 10 to about 60 weight percent of one or more aldehydes otherthan n-butyraldehyde.

In some embodiments, the resin composition, layer, or interlayer caninclude at least a first poly(vinyl acetal) resin and a secondpoly(vinyl acetal) resin, each of which may be present in thecomposition, layer, or interlayer in an amount of at least about 0.10,at least about 0.50, at least about 1, at least about 1.5, at leastabout 2, at least about 2.5, at least about 3, at least about 3.5, atleast about 5, at least about 10, at least about 15, at least about 20,at least about 30, at least about 40, or at least about 45 weightpercent, based on the combined weight of all resins in the composition,layer, or interlayer. Together, the first and second poly(vinyl acetal)resins can make up at least about 10, at least about 20, at least about30, at least about 40, at least about 50, at least about 60, at leastabout 70, or at least about 80 weight percent of all resins in thecomposition, layer, or interlayer. In some embodiments, the amount ofresins other than the first and second poly(vinyl acetal) resins can benot more than about 20, not more than about 15, not more than about 10,not more than about 5, not more than about 2, or not more than about 1weight percent, based on the combined weight of all resins.

The first and second poly(vinyl acetal) resin can be present in thecomposition in nearly the same amounts, or one of the first and secondpoly(vinyl acetal) resins can be present in a higher amount than theother. For example, in some embodiments, one of the first and secondpoly(vinyl acetal) resins can be present in an amount of at least about0.5, at least about 1, at least about 5, at least about 10, at leastabout 15, at least about 20, at least about 30 and/or not more thanabout 99.5, not more than about 90, not more than about 85, not morethan about 80, not more than about 70, not more than about 60, not morethan about 50, not more than about 40, not more than about 30, not morethan about 20 weight percent, or in the range of from about 0.5 to about99.5, about 10 to about 90, or about 30 to about 60 weight percent,based on the combined weight of the first and the second poly(vinylacetal) resins.

In some embodiments, one of the first and the second poly(vinyl acetal)resins can be present in the composition, layer, or interlayer in anamount of less than 12 weight percent, based on the combined weight ofthe first and second poly(vinyl acetal) resins. For example, the firstor the second poly(vinyl acetal) resin can be present in thecomposition, layer, or interlayer in an amount of at least about 0.3, atleast about 0.5, at least about 1, at least about 1.5, at least about 2,at least about 2.5, at least about 3, at least about 3.5, at least about4, at least about 4.5, at least about 5, at least about 5.5, at leastabout 6, at least about 6.5, at least about 7 weight percent and/or notmore than about 12, not more than about 11.5, not more than about 11,not more than about 10.5, not more than about 10, not more than about9.5, not more than about 9, not more than about 8.5, not more than about8, not more than about 7.5, or not more than about 5 weight percent,based on the combined weight of the first and second poly(vinyl acetal)resins. In some embodiments, one of the first and second poly(vinylacetal) resins can be present in the composition, layer, or interlayerin an amount in the range of from about 0.5 to about 12, about 1 toabout 10, about 1.5 to about 7.5, about 2.5 to about 5 weight percent,based on the combined weight of the first and second poly(vinyl acetal)resins.

The ratio, by weight, of one of the first and second poly(vinyl acetal)resin to the other can be at least about 0.3:99.7, at least about0.5:99.5, at least about 1:99, at least about 5:95, at least about10:90, at least about 15:85, at least about 20:80, at least about 25:75,at least about 40:60 and/or not more than about 99.7:0.3, not more thanabout 99.5:0.5, not more than about 99:1, not more than about 95:5, notmore than about 90:10, not more than about 85:15, not more than about80:20, not more than about 75:25, not more than about 60:40, or in therange of from about 0.3:99.7 to 99.7:0.3, about 10:90 to 90:10, about25:75 to about 75:25, or about 40:60 to 60:40.

In some embodiments, the resin composition, layer, or interlayer mayinclude at least a first poly(vinyl acetal) resin, a second poly(vinylacetal) resin, and a third poly(vinyl acetal) resin. According to theseembodiments, the first, second, and/or third poly(vinyl acetal) resinscan be present in the composition, layer, or interlayer in substantiallythe same amount, or one or more of the poly(vinyl acetal) resins may bepresent in an amount different than one or more of the other poly(vinylacetal) resins. At least one, at least two, or each of the threepoly(vinyl acetal) resins may be present in the composition, layer, orinterlayer in an amount of at least about 0.10, at least about 0.50, atleast about 1, at least about 2, at least about 3, at least about 5, atleast about 10, at least about 15, at least about 20, at least about 30,at least about 40, or at least about 45 weight percent, based on thecombined weight of all resins in the composition, layer, or interlayer.Together, the first, second, and third poly(vinyl acetal) resins canmake up at least about 10, at least about 20, at least about 30, atleast about 40, at least about 50, at least about 60, at least about 70,or at least about 80 weight percent of the resins in the composition,layer, or interlayer. In some embodiments, the amount of resins otherthan the first, second, and third poly(vinyl acetal) resins in thecomposition, layer, or interlayer can be not more than about 20, notmore than about 15, not more than about 10, not more than about 5, notmore than about 2, or not more than about 1 weight percent.

The first, second, and third poly(vinyl acetal) resins can be present inthe composition in nearly the same amounts, or at least one of thefirst, second, and third poly(vinyl acetal) resins can be present in ahigher amount than one or more of the others. For example, in someembodiments, at least one of the first, second, and third poly(vinylacetal) resins can be present in an amount of at least about 0.3, atleast about 0.5, at least about 1, at least about 5, at least about 10,at least about 15, at least about 20, at least about 30 and/or not morethan about 99.7, not more than about 99.5, not more than about 90, notmore than about 85, not more than about 80, not more than about 70, notmore than about 60, not more than about 50, not more than about 40, notmore than about 30, not more than about 20 weight percent, or in therange of from about 0.3 to about 99.7, about 10 to about 90, or about 30to about 60 weight percent, based on the combined weight of the first,second, and third poly(vinyl acetal) resins.

The ratio, by weight, of one of the first, second, and third poly(vinylacetal) resin to one or both of the others can be at least about0.3:99.7, at least about 1:99, at least about 5:95, at least about10:90, at least about 15:85, at least about 20:80, at least about 25:75,at least about 40:60 and/or not more than about 99.5:0.5, not more thanabout 99:1, not more than about 95:5, not more than about 90:10, notmore than about 85:15, not more than about 80:20, not more than about75:25, not more than about 60:40, or in the range of from about 0.3:99.7to 99.7:0.3, about 10:90 to 90:10, about 25:75 to about 75:25, or about40:60 to 60:40.

According to some embodiments, the first and second poly(vinyl acetal)resins present in the composition, layer, or interlayer may be blendedsuch that one of the first and second resins is dispersed within theother of the first and second resins, which can form domains of one ofthe first and second poly(vinyl acetal) resins within the other. Such ablended resin may be used as a single layer interlayer or it may becombined with one or more adjacent layers to form a multilayerinterlayer. In other embodiments, the first and second poly(vinylacetal) resins can be present in adjacent layers of a multilayerinterlayer, such that one of the layers of the interlayer includes thefirst poly(vinyl acetal) resin and another layer of the interlayerincludes the second poly(vinyl acetal) resin. Additional layers can alsobe present in the multilayer interlayer according to various embodimentsof the present invention.

The resin compositions, layers, and interlayers according to variousembodiments of the present invention can further include at least oneplasticizer. Depending on the specific composition of the resin orresins in a composition, layer, or interlayer, the plasticizer may bepresent in an amount of at least about 5, at least about 10, at leastabout 15, at least about 20, at least about 25, at least about 30, atleast about 35, at least about 40, at least about 45, at least about 50,at least about 55, at least about 60 parts per hundred parts of resin(phr) and/or not more than about 120, not more than about 110, not morethan about 105, not more than about 100, not more than about 95, notmore than about 90, not more than about 85, not more than about 75, notmore than about 70, not more than about 65, not more than about 60, notmore than about 55, not more than about 50, not more than about 45, ornot more than about 40 phr, or in the range of from about 5 to about120, about 10 to about 110, about 20 to about 90, or about 25 to about75 phr.

As used herein, the term “parts per hundred parts of resin” or “phr”refers to the amount of plasticizer present as compared to one hundredparts of resin, on a weight basis. For example, if 30 grams ofplasticizer were added to 100 grams of a resin, the plasticizer would bepresent in an amount of 30 phr. If the resin composition, layer, orinterlayer includes two or more resins, the weight of plasticizer iscompared to the combined amount of all resins present to determine theparts per hundred resin. Further, when the plasticizer content of alayer or interlayer is provided herein, it is provided with reference tothe amount of plasticizer in the mix or melt that was used to producethe layer or interlayer.

Examples of suitable plasticizers can include, but are not limited to,triethylene glycol di-(2-ethylhexanoate) (“3GEH”), triethylene glycoldi-(2-ethylbutyrate), triethylene glycol diheptanoate, tetraethyleneglycol diheptanoate, tetraethylene glycol di-(2-ethylhexanoate)(“4GEH”), dihexyl adipate, dioctyl adipate, hexyl cyclohexyl adipate,diisononyl adipate, heptylnonyl adipate, di(butoxyethyl) adipate, andbis(2-(2-butoxyethoxy)ethyl) adipate, dibutyl sebacate, dioctylsebacate, and mixtures thereof. The plasticizer may be selected from thegroup consisting of triethylene glycol di-(2-ethylhexanoate) andtetraethylene glycol di-(2-ethylhexanoate), or the plasticizer cancomprise triethylene glycol di-(2-ethylhexanoate).

According to some embodiments, the first and second poly(vinyl acetal)resins in the compositions, layers, and interlayers described herein canhave different compositions. Typically, such differences in compositionbetween the first and second poly(vinyl acetal) resins result inundesirable optical properties, such as increased haze and reducedclarity, when the resins are combined in a composition, layer, orinterlayer. However, as discussed in further detail below, inclusion ofat least one haze reducing agent or blending agent in accordance withembodiments of the present invention results in compositions, layers,and interlayers including such resin blends that exhibit enhancedclarity.

According to some embodiments, the first and second poly(vinyl acetal)resins may have different amounts of residual hydroxyl and/or acetategroups incorporated into the polymer backbone. As used herein, the terms“residual hydroxyl content” and “residual acetate content” refer to theamount of hydroxyl and acetate groups, respectively, that remain on aresin after processing is complete. For example, polyvinyl n-butyral canbe produced by hydrolyzing polyvinyl acetate to polyvinyl alcohol, andthen acetalizing the polyvinyl alcohol with n-butyraldehyde to formpolyvinyl n-butyral. In the process of hydrolyzing the polyvinylacetate, not all of the acetate groups are converted to hydroxyl groups,and residual acetate groups remain on the resin. Similarly, in theprocess of acetalizing the polyvinyl alcohol, not all of the hydroxylgroups are converted to acetal groups, which also leaves residualhydroxyl groups on the resin. As a result, most poly(vinyl acetal)resins include both residual hydroxyl groups (as vinyl alcohol groups)and residual acetate groups (as vinyl acetate groups) as part of thepolymer chain. The residual hydroxyl content and residual acetatecontent are expressed in weight percent, based on the weight of thepolymer resin, and are measured according to ASTM D-1396.

The difference between the residual hydroxyl content of the first andsecond poly(vinyl acetal) resins used in compositions, layers, andinterlayers according to various embodiments of the present inventioncould also be at least about 2, at least about 3, at least about 4, atleast about 6, at least about 8, at least about 10, at least about 12,at least about 15, at least about 20, or at least about 30 weightpercent. As used herein, the terms “weight percent different” and “thedifference is at least weight percent” refer to a difference between twogiven weight percentages, calculated by subtracting one number from theother number. For example, a poly(vinyl acetal) resin having a residualhydroxyl content of 12 weight percent and a poly(vinyl acetal) resinhaving a residual hydroxyl content of 14 weight percent are 2 weightpercent different from one another. As used herein, the term “different”encompasses values that are both higher and lower than another value.

In some embodiments, at least one of the first and second poly(vinylacetal) resins can have a residual hydroxyl content of at least about14, at least about 14.5, at least about 15, at least about 15.5, atleast about 16, at least about 16.5, at least about 17, at least about17.5, at least about 18, at least about 18.5, at least about 19, atleast about 19.5 and/or not more than about 45, not more than about 40,not more than about 35, not more than about 33, not more than about 30,not more than about 27, not more than about 25, not more than about 22,not more than about 21.5, not more than about 21, not more than about20.5, or not more than about 20 weight percent, or in the range of fromabout 14 to about 45, about 16 to about 30, about 18 to about 25, about18.5 to about 20, or about 19.5 to about 21 weight percent.

The other poly(vinyl acetal) resin can have a residual hydroxyl contentof at least about 8, at least about 9, at least about 10, at least about11 weight percent and/or not more than about 16, not more than about14.5, not more than about 13, not more than about 11.5, not more thanabout 11, not more than about 10.5, not more than about 10, not morethan about 9.5, or not more than about 9 weight percent, or in the rangeof from about 8 to about 16, about 9 to about 15, or about 9.5 to about14.5 weight percent. As mentioned previously, the poly(vinyl acetal)resins may be selected such that the difference between the residuahydroxyl content of one or more of the resins is at least about 2 weightpercent different than the residual hydroxyl content of one or moreother resins in the composition, layer, or interlayer.

One or more other poly(vinyl acetal) resins may also be present in theresin composition, layer, or interlayer and can have a residual hydroxylwithin the ranges provided above. Additionally, the residual hydroxylcontent of the one or more other poly(vinyl acetal) resins in thecomposition, layer, or interlayer can be the same as or different thanthe residual hydroxyl content of the first and/or second poly(vinylacetal) resins.

In some embodiments, the first poly(vinyl acetal) resin can have aresidual acetate content that is at least about 2, at least about 3, atleast about 4, at least about 5, at least about 6, or at least about 8,at least about 10, at least about 12, at least about 15, at least about20, or at least about 30 weight percent higher or lower than theresidual acetate content of the second poly(vinyl acetal) resin. Inother embodiments, the first poly(vinyl acetal) resin can have aresidual acetate content that is not more than about 5, not more thanabout 4, not more than about 3, not more than about 2, not more thanabout 1, or not more than about 0.5 weight percent higher or lower thanthe residual acetate content of the second poly(vinyl acetal) resin. Atleast one of the first and second poly(vinyl acetal) resins can have aresidual acetate content of not more than about 4, not more than about3, not more than about 2, or not more than about 1 weight percent,while, in other embodiments, at least one of the first and secondpoly(vinyl acetal) resins can have a residual acetate content of atleast about 5, at least about 8, at least about 10, at least about 12,at least about 14, at least about 16, at least about 18, at least about20, or at least about 30 weight percent. Additional poly(vinyl acetal)resins present in the resin composition or interlayer can have aresidual acetate content the same as or different than the residualacetate content of the first and/or second poly(vinyl acetal) resin, andthe value may fall in one or more of the ranges above.

In various embodiments, the differences in residual hydroxyl and/orresidual acetate content of the first and second poly(vinyl acetal)resins can be selected to control or provide certain performanceproperties, such as strength, impact resistance, penetration resistance,processability, or acoustic performance to the final composition, layer,or interlayer. For example, poly(vinyl acetal) resins having a higherresidual hydroxyl content, such as, for example, those greater thanabout 16 weight percent, can facilitate increased impact resistance,penetration resistance, and strength to a resin composition or layer,while lower hydroxyl content resins, such as, for example, those havinga residual hydroxyl content of less than 13 weight percent, can improvethe acoustic performance of the interlayer or blend.

Poly(vinyl acetal) resins having higher or lower residual hydroxylcontents and/or residual acetate contents, when combined with at leastone plasticizer, may ultimately include different amounts ofplasticizer. As a result, layers or domains formed of first and secondpoly(vinyl acetal) resins having different compositions may also havedifferent properties within a single resin layer or interlayer. Althoughnot wishing to be bound by theory, it is understood that thecompatibility of a given plasticizer with a poly(vinyl acetal) resin candepend, at least in part, on the composition of the polymer, and, inparticular, on its residual hydroxyl content. Overall, poly(vinylacetal) resins with higher residual hydroxyl contents tend to exhibit alower compatibility (or capacity) for a given plasticizer as compared tosimilar resins having a lower residual hydroxyl content. As a result,poly(vinyl acetal) resins with higher residual hydroxyl contents tend tobe less plasticized and exhibit higher stiffness than similar resinshaving lower residual hydroxyl contents. Conversely, poly(vinyl acetal)resins having lower residual hydroxyl contents may tend to, whenplasticized with a given plasticizer, incorporate higher amounts ofplasticizer, which may result in a softer resin layer that exhibits alower glass transition temperature than a similar resin having a higherresidual hydroxyl content. Depending on the specific resin andplasticizer, these trends could be reversed.

When two poly(vinyl acetal) resins having different levels of residualhydroxyl content are blended with a plasticizer, the plasticizer maypartition between the resin layers or domains, such that moreplasticizer can be present in the layer or domain having the lowerresidual hydroxyl content and less plasticizer may be present in thelayer or domain having the higher residual hydroxyl content. Ultimately,a state of equilibrium is achieved between the two resins. Thecorrelation between the residual hydroxyl content of a poly(vinylacetal) resin and plasticizer compatibility/capacity can facilitateaddition of a proper amount of plasticizer to the polymer resin. Such acorrelation also helps to stably maintain the difference in plasticizercontent between two or more resins when the plasticizer would otherwisemigrate between the resins.

In some embodiments, two or more resin layers or interlayers can beblended to thereby form new resin layers or interlayers havingunexpected properties and performance attributes. For example, a resinlayer or interlayer having lower residual hydroxyl content and lowerglass transition temperature may be blended with another resin layer orinterlayer having higher residual hydroxyl content and higher glasstransition temperature, resulting a new resin layer or interlayer havingsoft domains of lower glass transition temperature, which enhances itsacoustic performance, and stiff domains of higher glass transitiontemperature, which imparts enhanced processability, strength, and impactresistance to the resin layer or interlayer. In other embodiments, asingle sheet interlayer can be blended with a multilayer interlayer, twomultilayer interlayers can be blended, or one multilayer interlayer canbe blended into a resin layer of another multilayer interlayer. Theeffect arising from blending two materials can also be achieved fromblending two or more resins, plasticizers, and other additives accordingto the contents of the materials. For the clarity of the presentinvention, the discussion on the blend, including blend of resins andblend of resin layers or interlayers, have been centered on the blend ofresins throughout of the present invention. As used herein, a “blendresin material” or “blend material” refers to the resin composition,resin layer or interlayer to be blended into another resin composition,resin layer or interlayer. In blending two resin layers or twointerlayers, at least one of the two materials to be blended can includethe resin layer or interlayer of the present invention. In otherembodiments, both materials can include the resin layers or interlayersof the present invention.

In some embodiments, a resin layer or interlayer can include at least afirst resin layer comprising a first poly(vinyl acetal) resin and afirst plasticizer, and a second resin layer comprising a secondpoly(vinyl acetal) resin and a second plasticizer. The first layer maybe adjacent to the second layer and the first and second plasticizer canbe the same or different. When one of the first and second poly(vinylacetal) resins has a residual hydroxyl content that is at least 2 weightpercent higher or lower than the residual hydroxyl content of the other,the difference in plasticizer content between the resin layers can be atleast about 2, at least about 5, at least about 8, at least about 10, atleast about 12, or at least about 15 phr. In some embodiments, the resinlayer that includes the resin having a lower hydroxyl content can havethe higher plasticizer content. In order to control or retain otherproperties of the resin layer or interlayer, the difference inplasticizer content between the first and second resin layers may be notmore than about 100, not more than about 50, not more than about 45, notmore than about 40 phr, not more than about 35, not more than about 30,not more than about 20, not more than about 15, not more than about 10,not more than about 5 phr. In other embodiments, the difference inplasticizer content between the first and second resin layers may be atleast about 40, at least about 50, at least about 60, or at least about70 phr.

According to one embodiment, one of the resin layers can have aplasticizer content of at least about 42, at least about 45, at leastabout 50, at least about 55, at least about 60, at least about 65 phrand/or not more than about 120, not more than about 110, not more thanabout 90, not more than about 85, not more than about 80, or not morethan about 75 phr, or in the range of from about 50 to about 120, about55 to about 110, about 60 to about 90, or about 65 to about 75 phr. Oneor more other resin layers may have a plasticizer content of less than50 phr, not more than about 45 phr, not more than about 40 phr, not morethan about 38 phr, not more than about 30 phr, or not more than about 20phr.

In some embodiments, the first and second resin layers can exhibitdifferent glass transition temperatures. Glass transition temperature,or T_(g), is the temperature that marks the transition from the glassystate of the polymer to the rubbery state. The glass transitiontemperatures of the resins and layers described herein were determinedby dynamic mechanical thermal analysis (DTMA). The DTMA measures thestorage (elastic) modulus (G′) in Pascals, loss (viscous) modulus (G″)in Pascals, and the tan delta (G″/G′) of the specimen as a function oftemperature at a given oscillation frequency and temperature sweep rate.The glass transition temperature is then determined by the position ofthe tan delta peak on the temperature scale. Glass transitiontemperatures provided herein were determined at an oscillation frequencyof 1 Hz under shear mode and a temperature sweep rate of 3° C./min.

The difference between the glass transition temperatures of the firstresin layer and the second resin layer, or various regions of a blendedresin or resin layer, can be at least about 3, at least about 5, atleast about 8, at least about 10, at least about 12, at least about 15,at least about 18, at least about 20, at least about 22, or at leastabout 25° C. One of the first and second resins or resin layers can havea glass transition temperature of at least about 26, at least about 28,at least about 30, at least about 33, at least about 35° C. and/or notmore than about 70, not more than about 65, not more than about 60, notmore than about 55, not more than about 50, not more than about 45, notmore than about 40, or not more than about 35° C., or a glass transitiontemperature in the range of from about 26 to about 70° C., about 30 toabout 70° C., about 30 to about 65° C., or about 30 to about 40° C. Theother of the first and second poly(vinyl acetal) resins or resin layerscan have a glass transition temperature of less than 25, not more thanabout 20, not more than about 15, not more than about 10, not more thanabout 5, not more than about 0, not more than about −5, not more thanabout −10° C. In some embodiments, the difference between the glasstransition temperatures of various regions of a blended resin of thefirst and second resins might be indistinguishable by the T_(g)measurement.

When the first and second poly(vinyl acetal) resins are blended with oneanother such that domains of one resin are dispersed within the other,such differences in plasticizer content and/or glass transitiontemperature may also exist between domains of the first and secondresins. For example, in some embodiments, a resin layer or interlayermay include various domains of higher or lower plasticizer contentand/or domains having higher or lower glass transition temperatures, asdescribed previously. In some embodiments, at least a portion of theresin layer or interlayer can have a glass transition temperature of atleast about 25, at least about 27, at least about 30, at least about 33,at least about 35° C. and/or not more than about 70, not more than about65, not more than about 60, not more than about 55, not more than about50, not more than about 45, not more than about 40, or not more thanabout 35° C., or a glass transition temperature in the range of fromabout 25 to about 70° C., about 27 to about 65° C., or about 30 to about40° C. In some embodiments, at least a portion of the resin layer orinterlayer can have a glass transition temperature of less than 25, notmore than about 20, not more than about 15, not more than about 10, notmore than about 5, not more than about 0, not more than about −5, notmore than about −10° C.

One or more resin compositions, layers, and interlayers described hereinmay include various other additives to impart particular properties orfeatures to the interlayer. Such additives can include, but are notlimited to, dyes, pigments, stabilizers such as ultraviolet stabilizers,antioxidants, anti-blocking agents, flame retardants, IR absorbers orblockers such as indium tin oxide, antimony tin oxide, lanthanumhexaboride (LaB₆) and cesium tungsten oxide, processing aides, flowenhancing additives, lubricants, impact modifiers, nucleating agents,thermal stabilizers, UV absorbers, dispersants, surfactants, chelatingagents, coupling agents, adhesives, primers, reinforcement additives,and fillers.

Additionally, various adhesion control agents (“ACAs”) can be used inthe interlayers of the present disclosure to control the adhesion of thesheet to glass. In various embodiments, the amount of ACAs present in aresin composition, layer, or interlayer can be at least about 0.003, atleast about 0.01, at least about 0.025 and/or not more than about 0.15,not more than about 0.10, or not more than about 0.04 phr, or in therange of from about 0.003 to about 0.15, about 0.01 to about 0.10, orabout 0.025 to about 0.04 phr. Suitable ACAs can include, but are notlimited to, sodium acetate, potassium acetate, magnesium bis(2-ethylbutyrate), magnesium bis(2-ethylhexanoate), and combinations thereof, aswell as the ACAs disclosed in U.S. Pat. No. 5,728,472.

Resins having different compositions and plasticized resin layers havingdifferent properties also tend to exhibit different values for certainoptical properties, such as haze and visual transmittance, which canreduce the optical quality of the resulting layer or blend. However, invarious embodiments of the present invention, compositions, layers, andinterlayers that include at least a first poly(vinyl acetal) resin and asecond poly(vinyl acetal) resin may further include at least oneblending agent for increasing the compatibility of the first and secondpoly(vinyl acetal) resins with each other and/or for enhancing theoptical properties of the composition, layer, or interlayer.

According to one embodiment, the composition, layer, or interlayer caninclude at least one blending agent. As used herein, the term “blendingagent” refers to any agent or additive included in the composition,layer, or interlayer to facilitate blending of the components within thecomposition, layer, or interlayer. In some embodiments, the blendingagent can include at least two chemical functional groups, or moieties,that are more compatible with some of the poly(vinyl acetal) resins ascompared to others. For example, in some embodiments, the blending agentcan have at least one moiety that is more compatible with the firstpoly(vinyl acetal) resin than with the second poly(vinyl acetal) resinand at least one other moiety that is more compatible with the secondpoly(vinyl acetal) resin than with the first poly(vinyl acetal) resin.

In some embodiments, the blending agent may have a hydrophilic group anda lipophilic group and, as a result, may exhibit a higher tendency tohydrogen bond with one of the two poly(vinyl acetal) resins than withthe other of the poly(vinyl acetal) resins. The blending agent may alsoexhibit more polar-polar interactions with one of the two resins thanthe other of the two resins. Additionally, the blending agent may haveone moiety that has a higher hydrophobic-hydrophobic interaction withone of the two resins, and it may have at least one other moiety havinga higher hydrophilic-hydrophilic interaction with another of the tworesins.

The blending agent may include at least one hydrophobic segment and atleast one lipophilic segment and can, for example, have anhydrophobic-lipophilic balance (HLB) value of at least about 2, at leastabout 3, at least about 4, at least about 5, at least about 6, at leastabout 8 and/or not more than about 16, not more than about 15, not morethan about 14, not more than about 13, not more than about 12, not morethan about 10, not more than about 9, measured as described in“Polymeric Surfactants,” Surfactant Science Series, v. 42, p. 221, by I.Piirma (CRC Press, 1992). The HLB value for the blending agent may be inthe range of from about 2 to about 16, about 2 to about 15, about 3 toabout 14, about 6 to about 9, or about 8 to about 14. In someembodiments, the blending agent may be selected from the groupconsisting of glycols and glycol ethers, or, it may be selected from thegroup consisting of polyethylene glycol alkylphenol ethers including atleast 2 ethylene glycol units, monoalkyl ethylene glycol ethers, alkylalcohols, and low molecular weight polyethylene glycols, andcombinations thereof. In some embodiments, the blending agent may notinclude a compound selected from the group consisting of adipic acidesters, polyadipic acid esters, and combinations thereof. In someembodiments, the blending agent may include propylene glycol units orlow molecular weight polypropylene glycol

The blending agent may be present in the composition, layer, orinterlayer in any amount suitable to increase the compatibility of thefirst and second resin to a desired extent. In some embodiments, theblending agent may be present in an amount sufficient to provide thecomposition, layer, or interlayer with the optical and/or acousticproperties discussed in detail below. In some embodiments, the blendingagent may be present in the composition, layer, or interlayer in anamount sufficient that the composition, layer, or interlayer exhibitsonly a single glass transition temperature, rather than two distinctglass transition temperatures, as would be expected in a conventionalblend of poly(vinyl acetal) resins having differing compositions asdescribe above.

In various embodiments, the blending agent may be present in thecomposition in an amount of at least about 0.25, at least about 0.5, atleast about 1, at least about 1.5, at least about 2, at least about 2.5,at least about 5 weight percent and/or not more than about 50, not morethan about 40, not more than about 30, not more than about 20, not morethan about 15, not more than about 10, or not more than about 5 weightpercent, based on the total weight of the composition, layer, orinterlayer. The blending agent may be present in an amount in the rangeof from about 0.25 to about 60, about 0.5 to about 45, or about 1 toabout 30 weight percent, based on the total weight of the composition,layer, or interlayer. The composition, layer, or interlayer may furtherinclude at least one plasticizer of a type and in an amount as describedpreviously, or the blending agent itself may also act as a plasticizerfor the composition, layer, or interlayer.

According to some embodiments, a resin layer or interlayer is providedthat includes at least a first poly(vinyl acetal) resin, a secondpoly(vinyl acetal) resin, and at least one blending agent, present inthe composition in an amount sufficient to increase the compatibility ofthe first and second poly(vinyl acetal) resins. The layer or interlayercan have a single glass transition temperature of at least about −15, atleast about 0, at least about 5, at least about 10, at least about 15and/or not more than about 70, not more than about 65, not more thanabout 60, not more than about 55, not more than about 50, not more thanabout 45, not more than about 40, not more than about 35, not more thanabout 30, not more than about 25, not more than about 20° C., measuredas described previously. The glass transition temperature can be in therange of from about −10 to about 75° C., from about 0 to about 70° C.,about 0 to about 50° C., about 5 to about 45° C., or about 10 to about40° C. The layer or interlayer can optionally include at least oneplasticizer, along with one or more additional poly(vinyl acetal) resinsor additives, as discussed previously.

In some embodiments, a multiple layer interlayer is provided thatincludes at least a first resin layer and a second resin layer adjacentto the first resin layer. One of the layers can include a firstpoly(vinyl acetal) resin and the second resin layer may include, invarious embodiments, a blend of at least two poly(vinyl acetal) resins.When the second resin layer includes a blend of resins, one of theresins in the blend may have a different composition, such as adifferent residual hydroxyl content and/or different residual acetatecontent, than at least one other resin in the blend, and at least oneresin in the blend may have a composition similar to the firstpoly(vinyl acetal) resin present in the first resin layer.

For example, in some embodiments, one of the poly(vinyl acetal) resinspresent in the second resin layer may have a residual hydroxyl contentof at least 14 weight percent, while the other poly(vinyl acetal) resinin the second resin layer may have a residual hydroxyl content of lessthan 12 weight percent. The first poly(vinyl acetal) resin present inthe first resin layer may also have a residual hydroxyl content of atleast 14 weight percent and the residual hydroxyl content of the firstpoly(vinyl acetal) resin may be within about 2, within about 1, orwithin about 0.5 weight percent of the residual hydroxyl content of thehigher hydroxyl content resin in the other resin layer.

Typically, in the absence of a blending agent, the layers and interlayerincluding the first and second poly(vinyl acetal) resins as describedabove exhibit a haze value greater than 1 percent and/or would have twoor more glass transition temperatures corresponding to each of theindividual resins present in the blended layer. However, according toembodiments of the present invention, the layers and interlayersdescribed herein that include at least one blending agent exhibitblended resin layers having a single glass transition temperature and/ora low haze value. For example, layers and interlayers including a blendof first and second poly(vinyl acetal) resins can have a single glasstransition temperature of not more than about 70, not more than about65, not more than about 60, not more than about 55, not more than about50, not more than about 45, not more than about 40, not more than about35, not more than about 30, not more than about 25, not more than about20, or not more than about 18° C., measured as described above, and/or ahaze value of not more than about 5, not more than about 4, not morethan about 3, not more than about 2, not more than about 1 percent,measured as described below.

According to some embodiments of the present invention, resincompositions, layers, and interlayers that include a blend of two ormore poly(vinyl acetal) resin having different compositions and/orproperties can include at least one haze reducing agent. As used herein,the term “haze reducing agent” refers to any additive or agent thatreduces the haze of a composition, layer, or interlayer formed with twopoly(vinyl acetal) resins having different compositions as discussedpreviously. Haze reducing agents according to embodiments of the presentinvention can include at least two different chemical groups, ormoieties, one of which can have a higher affinity for one of the firstand second poly(vinyl acetal) resins, and one of which can have a higheraffinity for the other of the first and second poly(vinyl acetal)resins. When one of the moieties of the haze reducing agent has a higheraffinity for one of the poly(vinyl acetal) resins than another, it mayhave a higher tendency to hydrogen bond with the resin, it may exhibitmore polar-polar interactions with the resin, or it may exhibit morehydrophobic-hydrophobic or hydrophilic-hydrophilic interactions with theresins as compared to at least one of the other resins.

The haze reducing agent may be present in the resin composition, layer,or interlayer in an amount of at least about 0.25, at least about 0.5,at least about 1.0, at least about 1.5, at least about 2.0, at leastabout 2.5, at least about 5.0 and/or not more than about 20, not morethan about 15, not more than about 12, not more than about 10, not morethan about 8 weight percent, based on the total weight of the resincomposition, layer, or interlayer. The haze reducing agent can bepresent in an amount in the range of from about 0.25 to about 20, about0.5 to about 15, or about 1 to 12 weight percent, based on the totalweight of the resin composition, layer, or interlayer.

The haze reducing agent can be non-reactive with one or both poly(vinylacetal) resins in the composition, layer, or interlayer, and, in someembodiments, may be an aromatic haze reducing agent. In someembodiments, the haze reducing agent can include at least one estermoiety and at least one aliphatic moiety, each of which may have higheraffinity for one of the two poly(vinyl acetal) resins than for theother. Examples of suitable haze reducing agent can include, forexample, one or more compounds represented by formulas (I) through(III), below:

In formula (I), above, R₁ can be an aliphatic hydrocarbon group havingat least about 4, at least about 5, at least about 6, at least about 8and/or not more than about 50, not more than about 40, not more thanabout 30, not more than about 25 carbon atoms, or it can have between 4and 50 carbon atoms, between 4 and 40 carbon atoms, or between 4 and 30carbon atoms. In some embodiments, R₁ can be an aliphatic hydrocarbongroup having between 8 and 25 carbon atoms. R₁ can be a straight chainor branched hydrocarbon group and may or may not include additionalsubstituents such as halogens or other components. R₂ can be apoly(alkylene glycol) group that can include at least 1, at least 2, atleast 3, at least 4, at least 5, at least 6, or at least 8 repeatingunits.

In formula (II), R₃ can be a straight chain or branched aliphatichydrocarbon group having at least 2, at least 3, at least 4, at least 5,or at least 8 carbon atoms, and m can be at least 1, at least 2, atleast 3, or at least 4. R₃ may be non-cyclic.

In formula (III), R₄ and R₅ can be the same or different, and may eachinclude at least 2, at least 3, at least 4, at least 6, or at least 8carbon atoms. The combined number of carbon atoms in R₄ and R₅ can be atleast 8, at least 10, or at least 12.

Examples of suitable haze reducing agent can include, but are notlimited to, nonylphenol ethoxylates having at least 1, at least 2, atleast 4, at least 6, at least 8, or at least 10 repeating ethyleneglycol units.

Resin compositions, layers, and interlayers formulated according tovarious embodiments of the present invention that include at least twopoly(vinyl acetal) resins and a blending agent or a haze reducing agentmay exhibit enhanced optical properties. For example, the compositions,layers, and interlayers described herein may have a higher clarity,lower haze, and/or lower mottle than compositions, layers, andinterlayers formulated in the absence of the blending or haze reducingagents.

Clarity can be used to describe the composition, layer, or interlayerdisclosed herein. Clarity is determined by measuring the haze value orpercent haze. The test for percent haze is performed with a hazemeter,such as Model D25 available from Hunter Associates (Reston, Va.), and inaccordance with ASTM D1003-13, Procedure B using Illuminant C, at anobserver angle of 2 degrees. The polymer interlayers are laminated witha pair of clear glass sheets each of 2.3 mm thick (commerciallyavailable from Pittsburgh Glass Works of Pennsylvania).

The clarity of a composition, layer, or interlayer is related to itshaze value. Haze value represents a quantification of light scattered bya sample as compared to the incident light. In some embodiments, thehaze value of a sample may be low, such as, for example, less than 2percent, however, when a bright light is shone on the laminates frombehind, an optical defect appearing as a “milky haze,” can be seen whenthe laminates are viewed at wide angles (>30°). The presence or absenceof such a “milky haze” is characterized herein by the HLD haze value.HLD haze is measured by a HLD haze measurement apparatus, which isconstructed with a tungsten halogen light source, a sample holder, agoniometer with a light detector mounted on. The HLD haze measurementapparatus is calibrated using a set of HLD standard laminates having atotal thickness of 8.3 mm (5 layers of 0.76 mm interlayer) between two2.3-mm clear glass sheets representing HLD Haze grades 0, 1, 2, and thelike, with increasing values indicating increased HLD haze. In thismeasurement, laminate was made with clear glass having thickness ofabout 2.3 mm by normal autoclave lamination process. After theautoclave, the laminate was placed at room temperature overnight. Thescatted light intensity at a scatted angle of 45° is collected from atesting laminate sample at room temperature using the HLD hazemeasurement apparatus, and HLD haze is calculated using a computersoftware and reported at a nominal total laminate thickness.

In some embodiments, the resin blends, layers, and interlayers describedherein may have an HLD value of less than 5, less than about 4, lessthan about 3, less than about 2, less than about 1, or less than about0.5. According to some embodiments, the compositions, layers, andinterlayers including a haze reducing agent or blending agent asdescribed herein may exhibit an HLD haze value that is at least about 1,at least about 2, at least about 5, at least about 8, at least about 10and/or not more than about 50, not more than about 30, not more thanabout 25, not more than about 20 percent lower than the HLD haze valueof an identical composition, layer, or interlayer formulated in theabsence of the blending agent or haze reducing agent. The HLD haze valuecan be in the range of from about 1 to about 50, about 2 to about 30, orabout 10 to about 20 percent lower than the HLD haze value of anidentical composition, layer, or interlayer formulated in the absence ofthe blending agent or haze reducing agent.

As used herein, the term “identical” used with reference to acomposition, layer, or interlayer refers to a composition, layer, orinterlayer formulated with identical poly(vinyl acetal) resin, havingthe same type and amount of aldehyde residues and the same residualhydroxyl and acetate contents, and present in the same amounts as agiven composition, layer, or interlayer. When the composition, layer, orinterlayer includes a plasticizer, an “identical” resin composition,layer, or interlayer includes a plasticizer of the same type and in thesame amount as the specified composition, layer, or interlayer.

In some embodiments, as discussed above, at least a portion of the resinlayer or interlayer may have a glass transition temperature of less than25, not more than about 20, not more than about 15, not more than about10, not more than about 5, not more than about 2, not more than about 1,not more than about 0, not more than about −5, not more than about −10°C., not more than about −15° C., which may facilitate its improvedacoustic performance. At the same time, at least a portion of the layeror interlayer may have a glass transition temperature of at least about26, at least about 30, at least about 35, at least about 40, at leastabout 45° C., which may facilitate impact resistance properties andstrength. As discussed previously, blends of polyvinyl acetal resinshaving different compositions, but including a blending agent mayexhibit a single glass transition temperature that falls within one ormore of the ranges provided above.

Additionally, the resin layers and interlayers can have a damping lossfactor of at least about 0.10, at least about 0.15, at least about 0.17,at least about 0.20, at least about 0.25, at least about 0.27, at leastabout 0.30, at least about 0.33, or at least about 0.35. Loss factor wasmeasured by Mechanical Impedance Measurement as described in ISOStandard 16940. A polymer sample was laminated between two sheets ofclear glass, each having a thickness of 2.3 mm, and was prepared to havea width of 25 mm and a length of 300 mm. The laminated sample was thenexcited at the center point using a vibration shaker, commerciallyavailable from Brüel and Kjær (Nærum, Netherlands) and an impedance headwas used to measure the force required to excite the bar to vibrate andthe velocity of the vibration. The resultant transfer function wasrecorded on a National Instrument data acquisition and analysis systemand the loss factor at the first vibration mode was calculated using thehalf power method. The resin compositions, layers, and interlayersdescribed above may be produced according to any suitable method. Invarious embodiments, the method for producing these compositions,layers, and interlayers can include providing two or more poly(vinylacetal) resins, blending the resins with at least one blending agentand/or at least one haze reducing agent and, optionally, at least oneplasticizer or other additive, to form a blended composition, andforming a layer from the blended composition.

In some embodiments, the resins provided in the initial steps of themethod can be in the form of one or more poly(vinyl acetal) resins. Thestep of blending of the two resins can comprise melt blending and may beperformed at a temperature of at least about 100, at least about 150, atleast about 200° C. Additionally, a portion of the blending step caninclude blending one or more of the resins with at least one plasticizerand/or with one or more of the blending agents or haze reducing agentsdescribed previously. The step of blending of two blend materials can bedone similar to the blending of the two resins.

The resulting blended resins can then be formed into one or more resinlayers or interlayers according to any suitable method. Exemplarymethods of forming polymer layers and interlayers can include, but arenot limited to, solution casting, compression molding, injectionmolding, melt extrusion, melt blowing, and combinations thereof.Multilayer interlayers including two or more resin layers may also beproduced according to any suitable method such as, for example,co-extrusion, blown film, melt blowing, dip coating, solution coating,blade, paddle, air-knife, printing, powder coating, spray coating, andcombinations thereof. In various embodiments of the present invention,the layers or interlayers may be formed by extrusion or co-extrusion. Inan extrusion process, one or more thermoplastic polymers, plasticizers,and, optionally, at least one additive, including one or more blendingor haze reducing agents as described previously, can be pre-mixed andfed into an extrusion device. Other additives, such as ACAs, colorants,and UV inhibitors, which can be in liquid, powder, or pellet form, mayalso be used and may be mixed into the thermoplastic polymers orplasticizers prior to entering the extrusion device. These additives canbe incorporated into the polymer resin and, by extension, the resultantpolymer sheet, thereby enhancing certain properties of the polymer layeror interlayer and its performance in the final multiple layer glasspanel or other end product.

In various embodiments, the thickness, or gauge, of the layers orinterlayers can be at least about 10, at least about 15, at least about20 mils and/or not more than about 100, not more than about 90, not morethan about 60, not more than about 50, or not more than about 35 mils,or it can be in the range of from about 10 to about 100, about 15 toabout 60, or about 20 to about 35 mils. In millimeters, the thickness ofthe polymer layers or interlayers can be at least about 0.25, at leastabout 0.38, at least about 0.51 mm and/or not more than about 2.54, notmore than about 2.29, not more than about 1.52, or not more than about0.89 mm, or in the range of from about 0.25 to about 2.54 mm, about 0.38to about 1.52 mm, or about 0.51 to about 0.89 mm. In some embodiments,the resin layers or interlayers can comprise flat polymer layers havingsubstantially the same thickness along the length, or longest dimension,and/or width, or second longest dimension, of the sheet, while, in otherembodiments, one or more layers of a multilayer interlayer, for example,can be wedge-shaped or can have a wedge-shaped profile, such that thethickness of the interlayer changes along the length and/or width of thesheet, such that one edge of the layer or interlayer has a thicknessgreater than the other.

In some embodiments of the present invention, the resin composition,layer, or interlayer can include at least one recycled resin material.As used herein, the term “recycled material” refers to a resin layer orinterlayer that has been removed from and subsequently returned to thesame or a different production line. In some embodiments, the resincomposition, layer, or interlayer can include at least one reworkedmaterial. As used herein, the term “reworked material” refers to a resinlayer or resin interlayer that has been removed from and subsequentlyreturned to the same production line. When the type and/or amount ofresins and plasticizers being recycled or reworked differs from those inthe poly(vinyl acetal) resin being produced, the opticalcharacteristics, such as clarity and haze, of the resulting resincomposition, layer, or interlayer can be adversely impacted. However,use of a haze reducing or blending agent as described above may resultin layers or interlayers including recycled or reworked materials, buthaving improved optical properties. It should be understood that thetype and/or amount of recycled or reworked resin material used in layersand interlayers in various embodiments of the present invention may fallwithin one or more of the ranges described previously and the layer orinterlayer may further include at least one haze reducing agent and/orat least one blending agent as described herein.

The resin compositions, layers, and interlayers according to embodimentsof the present invention may be utilized in a multiple layer panel thatcomprises a resin layer or interlayer and at least one rigid substrate.Any suitable rigid substrate may be used and in some embodiments may beselected from the group consisting of glass, polycarbonate, acrylic, andcombinations thereof. In some embodiments, the multilayer panels includea pair of rigid substrates with the resin interlayer disposedtherebetween. The panels can be used for a variety of end useapplications, including, for example, for automotive windshields andwindows, aircraft windshields and windows, structural architecturalpanels, decorative architectural panels, and other similar applications.

When laminating the resin layers or interlayers between two rigidsubstrates, such as glass, the process can include at least thefollowing steps: (1) assembly of the two substrates and the interlayer;(2) heating the assembly via an IR radiant or convective device for afirst, short period of time; (3) passing the assembly into a pressurenip roll for the first de-airing; (4) heating the assembly for a shortperiod of time to about 60° C. to about 120° C. to give the assemblyenough temporary adhesion to seal the edge of the interlayer; (5)passing the assembly into a second pressure nip roll to further seal theedge of the interlayer and allow further handling; and (6) autoclavingthe assembly at temperature between 135° C. and 150° C. and pressuresbetween 150 psig and 200 psig for about 30 to 90 minutes. Other methodsfor de-airing the interlayer-glass interface, as described according tosome embodiments in steps (2) through (5) above include vacuum bag andvacuum ring processes, and both may also be used to form interlayers ofthe present invention as described herein.

In some embodiments, the multiple layer panel may include at least onepolymer film disposed on the layer or interlayer, forming a multiplelayer panel referred to as a “bilayer.” In some embodiments, theinterlayer utilized in a bilayer may include a multilayer interlayer,while, in other embodiments, a monolithic interlayer may be used. Theuse of a polymer film in multiple layer panels as described herein mayenhance the optical character of the final panel, while also providingother performance improvements, such as infrared absorption. Polymerfilms differ from polymer layers or interlayers in that the films alonedo not provide the necessary penetration resistance and glass retentionproperties. The polymer film can also be thinner than the sheet, and mayhave a thickness in the range of from 0.001 to 0.25 mm. Poly(ethyleneterephthalate) (“PET”) can be one example of a material used to form thepolymer film in a bilayer.

The following examples are intended to be illustrative of the presentinvention in order to teach one of ordinary skill in the art to make anduse the invention and are not intended to limit the scope of theinvention in any way.

EXAMPLES

The following Examples describe the preparation of several resincompositions, layers, and interlayers that include blends of two or morepoly(vinyl acetal) resins having different compositions, some of whichfurther included at least one blending agent or haze reducing agent. Asdescribed below, several tests performed on many of the compositions,layers, and interlayers were used to evaluate the acoustic and opticalproperties of several comparative and disclosed materials.

Example 1: Preparation of Poly(Vinyl Acetal) Resin Layers

Comparative Resin Layer, CL-1 and CL-2, were prepared by combining oneor more of polyvinyl n-butyral resins having different residual hydroxylcontents in amounts as shown in Table 1, below. The first polyvinylbutyral resin (PVB-1) has a residual hydroxyl content of about 19 weightpercent and a residual acetate content of about 2 weight percent. Thesecond polyvinyl butyral resin (PVB-2) had a residual hydroxyl contentof about 13.3 weight percent and a residual acetate content of about 2weight percent. Each resin layer also included the plasticizertri-ethylene glycol-bis-2-ethylhexanoate (3GEH), which was present ineach layer in the amount shown in Table 1. The mixture of resin andplasticizer was melt mixed in a Braebender mixer at a temperature of170° C. for 7 minutes and the resulting melt was pressed into sheetshaving a thickness of 0.76 mm. The glass transition temperature of thesheet was measured and the results are provided in Table 1, below.

The Disclosed Resin Layers, DL-1 through DL-7, were prepared in asimilar manner as Comparative Resin Layers CL-1 and CL-2 describedabove, but included 25 parts by weight of the first resin (PVB-1) and 25parts by weight of the second resin (PVB-2), and varying amount of 3GEHand blending agent. Disclosed Resin Layers DL-1 through DL-7 includedvarious types and amounts of blending agents, each of which includednonylphenol polyethylene glycol having a different number of mole unitsof ethylene glycol. Blending Agent A included 4 mole units of ethyleneglycol, Blending Agent B included 6 mole units of ethylene glycol, andBlending agent C included 10 mole units of ethylene glycol. Blendingagents A, B, and C are commercially available as SURFONIC® N-40, N-60,and N-102, respectively, from Huntsman Chemical Company, The Woodlands,Tex. The blending agents were mixed with the resins in the amounts shownin Table 1. Each of the resulting blended melt mixtures was pressed intoa sheet having a thickness of 0.76 mm, and the glass transitiontemperature and haze of the sheet were determined as described above.The results are provided in Table 1, below.

TABLE 1 Glass Transition Temperatures and Haze for Several PVB ResinSheets PVB Blending Blending Blending Haze per Sheet PVB-1 PVB-2 3GEHAgent A Agent B Agent C T_(g)-1 T_(g)-2 ASTM D1003 Layer (parts) (parts)(parts) (grams) (grams) (grams) (° C.) (° C.) (%) CL-1 — 50 25 — — — nd16.9 0.6 CL-2 25 25 25 — — — 12.3 32.5 61.3 DL-1 25 25 15 — 10 — 17.6 nd19.3 DL-2 25 25 12.5 — 12.5 — 18.8 nd 13.2 DL-3 25 25 — — 25 — 27.4 nd4.8 DL-4 25 25 12.5 12.5 — — 16.1 nd 12.5 DL-5 25 25 — 25 — — 21.3 nd2.3 DL-6 25 25 12.5 — — 12.5 19.5 nd 4.3 DL-7 25 25 — — — 25 23.4 nd 2.6nd = not determined

As shown in Table 1, above, the sheet formed from Comparative ResinLayer CL-2 exhibited two distinct glass transition temperatures, whichindicates that PVB1 and PVB2 formed a phase-separated blend within thatlayer, and a high level of haze. However, as shown in Table 1, additionof Blending Agents A, B, or C in Disclosed Resins DL-1 to DL-7facilitated blending of the two resins, PVB-1 and PVB-2, to form acompatible resin blend that exhibited a single glass transitiontemperature and significantly reduced haze level. Additionally, as shownby Disclosed Resin Layer DL-1, DL-2, DL-4, and DL-6, an additionalplasticizer, such as 3GEH, can be used with these blends, but, as shownby Disclosed Resin Layers DL-3, DL-5, and DL-7, it is not required.However, when an additional plasticizer was included, the blendexhibited a lower glass transition temperature, as shown by comparisonof DL-1, DL-2, DL-4, or DL-6 in Table 1.

Additional Comparative Resin Layers CL-3 and CL-4 and Disclosed ResinLayers DL-8 through DL-13 were prepared in a similar manner as describedabove. The first polyvinyl butyral resin, PVB-3, used in each ofComparative Resin Layers CL-3 and CL-4 and Disclosed Resin Layers DL-1through DL-7, had a residual hydroxyl content of about 21 weight percentand a residual acetate content of about 2 weight percent. The secondpoly(vinyl n-butyral) resin (PVB-4) had a residual hydroxyl content ofabout 11 weight percent and a residual acetate content of about 2 weightpercent. Each of Disclosed Resin Layers D-8 through D-13 were preparedwith at least one Blending Agent A, B, and C, as described above. Thecomposition of each of Comparative Resin Layers CL-3 and CL-4 andDisclosed Resin Layers DL-8 through DL-13 are summarized in Table 2,below. The glass transition temperature, haze, and damping loss factorfor each of Comparative Resin Layers CL-3 and CL-4 were measured asdiscussed above, and the results are summarized in Table 2, below.

TABLE 2 Glass Transition Temperatures and Haze for Several AdditionalPVB Resin Sheets Blending Blending Blending Haze per Loss PVB-3 PVB-43GEH Agent A Agent B Agent C T_(g)-1 T_(g)-2 ASTM D1003 Factor Sample(parts) (parts) (parts) (grams) (grams) (grams) (° C.) (° C.) (%) (η)CL-3 30 20 26 — — — −4 35 94 0.13 CL-4 20 30 30 — — — −4 35 93 0.37 DL-830 20 — 26 — — 21.2 N.A 10.3 0.32 DL-9 20 30 — 30 — — 15.7 N.A 12.2 0.76DL-10 30 20 — — 26 — 22.7 N.A 6.7 0.43 DL-11 20 30 — — 30 — 15.2 N.A 90.72 DL-12 30 20 — — — 26 26.9 N.A 7.5 0.12 DL-13 20 30 — — — 30 16.7N.A 8.6 0.37

As shown in Table 2, above, the sheets formed from Comparative ResinLayers CL-3 and CL-4 each exhibited two distinct glass transitiontemperatures, which indicates that PVB-3 and PVB-4 in each of the sheetsformed a phase-separated blend within the layer, which resulted in ahigh level of haze. However, as shown in Table 2, addition of one ofBlending Agents A, B, or C in Disclosed Resins DL-8 to DL-13 facilitatedblending of the two resins, PVB-3 and PVB-4, into a resin blend thatexhibited a single glass transition temperature and a significantlyreduced haze level. The addition of a blending agent also did not affectthe damping loss factor of the layers resulting from the blend of PVB-3and PVB-4, and in some cases, lead to an increase in the damping lossfactor, as shown in Table 2, as compared to resin layers that did notinclude a blending agent. For example, Disclosed Resin Layers DL-9 andDL-11 exhibited a damping loss factor of 0.76 and 0.72, respectively,which are considerably higher than that of Comparative Resin Layer CL-4,which was 0.37. Additionally, as shown above, Disclosed Resin LayersDL-8 and DL-10 had damping loss factors of 0.32 and 0.43, respectively,which were also higher than that of Comparative Resin Layer CL-3, whichwas 0.13. As discussed previously and as shown in Table 2, the blendingagent, when properly selected, may not only facilitate blending betweentwo different resins, but may also improve sound insulation, as measuredby increased damping loss factor.

Disclosed Resin Layers DL-14 through DL-20 were prepared in a similarfashion as the resin layers discussed above with respect to Table 1. Thefirst and second polyvinyl butyral resins, PVB-3 and PVB-4, were thesame resins used to form the resin layers summarized in Table 2. Severalof the Disclosed Resin Layers included Blending Agent A, as describedabove, and several of the Resin Layers further included at least onehaze reducing agent. Haze Reducing Agent A was a propylene glycoldibenzoate and Haze Reducing Agent B was a diethylene glycol dibenzoate,both of which are commercially available as Benzoflex™ 284 andBenzoflex™ 2-45, both commercially available from Eastman ChemicalCompany, Kingsport, Tenn. The composition of each of Disclosed ResinLayers DL-14 through DL-20 are summarized in Table 3, below, along withthe haze of each resin layer, measured as described above.

TABLE 3 Haze Values for Several Additional PVB Resin Sheets Haze HazeBlending Reducing Reducing Haze per PVB-3 PVB-4 Agent A Agent A Agent BASTM D1003 Sample (parts) (parts) (parts) (parts) (parts) (%) DL-14 2525 25 — — 11 DL-15 25 25 10 15 — 3.6 DL-16 25 25 13 12.5 — 5.1 DL-17 2525 15 10 — 7.1 DL-18 25 25 10 — 15 1.4 DL-19 25 25 13 — 12.5 3.0 DL-2025 25 15 — 10 4

As shown in Table 3, use of a haze reducing agent, such as Haze ReducingAgent A or B, further reduced the haze of the resin blends that includeda blending agent. In addition, increasing the amount of haze reducingagent in the resin layers affords additional reduction in haze of theresin layer that included a blend of two distinctive resin composition.

Example 2: Resin Layers Including Various PVB Blends

Several blends of polyvinyl n-butyral resins (PVB) of varying hydroxylcontents were formed in order to simulate blends of resins having alower residual hydroxyl content with resins having a higher residualhydroxyl content. For this example, each resin blend included apoly(vinyl n-butyral) resin (PVB-1) and another poly(vinyl n-butyral)resin having a residual hydroxyl content of 11 weight percent and aresidual acetate content of about 2 weight percent (PVB-4). Each blendalso included varying amounts of 3GEH as a plasticizer. Some resinblends included 1.4 weight percent of PVB-4, while others included 2.8weight percent PVB-4, based on the total combined weight of the resins.

Several resin compositions were then formed by combining several of theresin blends with various amounts of one of the following blending orhaze reducing agents: bis(2-ethylhexyl) terephthalate, commerciallyavailable as Eastman 168™ from Eastman Chemical Company, Kingsport,Tenn. (Haze Reducing Agent H-1); a benzoate ester, commerciallyavailable as Benzoflex™ 9-88 from Eastman Chemical Company (HazeReducing Agent H-2); nonylphenol 12-mole ethoxylate, commerciallyavailable as SURFONIC® N-102 from Huntsman Chemical Company, TheWoodlands, Tex. (Blending Agent B-1); poly(propylene glycol)dibenzoate,commercially available as UNIPLEX 400 from Unitex Chemical Company,Greensboro, N.C. (Haze Reducing Agent H-3); and nonylphenolhexaethoxylate, commercially available as SURFONIC® N-60 also fromHuntsman Chemical Company (Blending Agent B-2).

Each composition was then melt mixed in a Braebender mixer at atemperature of 170° C. for 7 minutes and the resulting melt was pressedinto a sheet having a thickness of about 0.76 mm in order to formDisclosed Resin Layers DL-14 through DL-33. The glass transitiontemperatures of some of the sheets were measured and are provided inTable 4, below. Each sheet was formed into a laminate using a pair ofclear glass plates having a thickness of 2.3 mm at standard nip rolllamination conditions. The HLD haze value of each laminate was measuredas described above and the results are also summarized in Table 4,below. Table 4 also provides the percent reduction in haze exhibited byeach Disclosed Resin sheet as compared to with the haze value of aComparative Resin Sheet (CR-5 or CR-6) formulated with either 1.4 weightpercent (PVB-4) or 2.8 weight percent (PVB-4), but without a hazereducing agent.

TABLE 4 Properties of Various Resin Blends Haze Reducing Resin BlendComposition PVB3 Agent Haze Resin PVB4 PVB1 3GEH Haze Reducing orBlending Agent (g) (wt % of (wt % of T_(g) HLD Reduction Sheet (g) (g)(g) H1- H-2 B-1 H-3 B-2 resins) blend) (° C.) Haze (%) CL-5 1.4 48.619.5 — — — — — 2.8% 0.0% 30.9 2.30 — DL-14 1.4 48.6 17.0 2.5 — — — —2.8% 3.6% 31.7 1.70 26.1% DL-15 1.4 48.6 14.5 5  — — — — 2.8% 7.2% 33.11.20 47.8% DL-16 1.4 48.6 17.0 — 2.5 — — 2.8% 3.6% 30.5 0.80 65.2% DL-171.4 48.6 14.5 — 5  — — — 2.8% 7.2% 30.5 0.50 78.3% DL-18 1.4 48.6 17.0 —— 2.5 — — 2.8% 3.6% 30.0 0.60 73.9% DL-19 1.4 48.6 14.5 — — 5  — — 2.8%7.2% 29.4 1.20 47.8% DL-20 1.4 48.6 17.0 — — — 2.5 — 2.8% 3.6% 30.8 1.6030.4% DL-21 1.4 48.6 14.5 — — — 5  — 2.8% 7.2% 31.5 1.20 47.8% DL-22 1.448.6 17.0 — — 2.5 — — 2.8% 3.6% nd 2.01 12.7% DL-23 1.4 48.6 18.0 — —1.5 — — 2.8% 2.2% nd 1.22 46.8% DL-24 1.4 48.6 18.5 — — 1  — — 2.8% 1.4%nd 1.54 32.9% DL-25 1.4 48.6 17.0 — — — — 2.5 2.8% 3.6% nd 0.92 60.0%DL-26 1.4 48.6 18.0 — — — — 1.5 2.8% 2.2% nd 0.76 67.0% CL-6 0.7 49.319.0 — — — — — 1.4% 0.0% nd 0.48 — DL-27 0.7 49.3 16.5 — — 2.5 — — 1.4%3.6% nd 0.23 51.7% DL-28 0.7 49.3 17.5 — — 1.5 — — 1.4% 2.2% nd 0.4310.0% DL-29 0.7 49.3 18.0 — — 1  — — 1.4% 1.4% nd 0.44  8.3% DL-30 0.749.3 16.5 — 2.5 — — — 1.4% 3.6% nd 0.42 11.7% DL-31 0.7 49.3 17.5 — 1.5— — — 1.4% 2.2% nd 0.34 28.3% DL-32 0.7 49.3 17.5 — — — — 2.5 1.4% 3.6%nd 0.38 21.7% DL-33 0.7 49.3 16.5 — — — — 1.5 1.4% 2.2% nd 0.43 10.0% nd= not determined

As shown in Table 4, above, the Disclosed Resin blends that included ahaze reducing agent or a blending agent exhibited lower haze values thansimilar Comparative Resin blends that did not include such agents.Additionally, as shown in Table 4, Haze Reducing Agents H-1 through H-3and Blending Agents B-1 and B-2 were effective to reduce the haze ofcompositions that included varying amounts of PVB-4, which had lowerresidual hydroxyl content. Surprisingly, some blends having a higherPVB-4 concentration actually demonstrated increased haze reduction, ascompared to those having a lower concentration of PVB-3.

While the invention has been disclosed in conjunction with a descriptionof certain embodiments, including those that are currently believed tobe the preferred embodiments, the detailed description is intended to beillustrative and should not be understood to limit the scope of thepresent disclosure. As would be understood by one of ordinary skill inthe art, embodiments other than those described in detail herein areencompassed by the present invention. Modifications and variations ofthe described embodiments may be made without departing from the spiritand scope of the invention

It will further be understood that any of the ranges, values, orcharacteristics given for any single component of the present disclosurecan be used interchangeably with any ranges, values or characteristicsgiven for any of the other components of the disclosure, wherecompatible, to form an embodiment having defined values for each of thecomponents, as given herein throughout. For example, an interlayer canbe formed comprising poly(vinyl butyral) having a residual hydroxylcontent in any of the ranges given in addition to comprising aplasticizers in any of the ranges given to form many permutations thatare within the scope of the present disclosure, but that would becumbersome to list. Further, ranges provided for a genus or a category,such as phthalates or benzoates, can also be applied to species withinthe genus or members of the category, such as dioctyl terephthalate,unless otherwise noted.

What is claimed is:
 1. A mixed resin composition comprising: a firstpoly(vinyl acetal) resin; a second poly(vinyl acetal) resin, wherein theresidual hydroxyl content and/or said residual acetate content of saidsecond poly(vinyl acetal) resin is at least 2 weight percent higher orlower than the residual hydroxyl content and/or residual acetate contentof said first poly(vinyl acetal) resin, wherein said second poly(vinylacetal) resin is present in said resin composition in an amount of from0.3 to 12 weight percent, based on the total weight of said first andsaid second poly(vinyl acetal) resins; and a haze reducing agent,wherein said haze reducing agent has at least one moiety having a higheraffinity for said first poly(vinyl acetal) resin than for said secondpoly(vinyl acetal) resin and at least one other moiety having a higheraffinity for said second poly(vinyl acetal) resin than for said firstpoly(vinyl acetal) resin, wherein said haze reducing agent is present insaid composition in an amount in the range of from 0.25 to 20 weightpercent, based on the total weight of said composition; wherein saidcomposition further comprises a third poly(vinyl acetal) resin, whereinsaid first, second, and third poly(vinyl acetal) resin are each presentin said resin composition in an amount of at least 0.3 weight percent,based on the total weight of said first, second, and third poly(vinylacetal) resins.
 2. The composition of claim 1, wherein said hazereducing agent is selected from the group consisting of the compoundsrepresented by formulas (I) through (III), below—

wherein R₁ is an aliphatic hydrocarbon group having between 4 and 50carbon atoms, and wherein R₂ is a poly(alkylene glycol) group includesat least 2 poly(alkylene glycol) repeat units;

wherein R₃ is an aliphatic hydrocarbon group having at least 2 carbonatoms, and wherein m is at least 1; and

wherein R₄ and R₅ are the same or different hydrocarbon groups, eachcomprising at least 2 carbon atoms and wherein the total number ofcarbon atoms in R₄ and R₅ is at least
 8. 3. The composition of claim 2,wherein said composition meets at least one of criteria (i) through (iv)below— (i) said haze reducing agent comprises a compound represented byformula (I) and wherein R₁ is a branched or linear aliphatic hydrocarbongroup having between 4 and 30 carbon atoms; (ii) said haze reducingagent comprises a compound represented by formula (I) and wherein R₂includes at least 4 alkylene glycol repeat units; (iii) said hazereducing agent comprises a compound represented by formula (II) andwherein R₃ is a branched or linear aliphatic hydrocarbon group, and (iv)said haze reducing agent comprises a compound represented by formula(III) and wherein the total number of carbon atoms of R₄ and R₅ is atleast
 12. 4. The composition of claim 1, wherein said haze reducingagent is present in said composition in an amount of at least about 0.5weight percent, based on the total weight of said composition, andwherein each of said first and said second poly(vinyl acetal) resins ispresent in said composition in an amount of at least about 1 weightpercent, based on the total weight of resins in said composition.
 5. Thecomposition of claim 1, wherein the residual hydroxyl content of saidsecond poly(vinyl acetal) resin is at least 2 weight percent lower thanthe residual hydroxyl content of said first poly(vinyl acetal) resin,and wherein the residual hydroxyl content of said second poly(vinylacetal) resin is not more than 16 weight percent.
 6. The composition ofclaim 1, further comprising, at least one plasticizer present in saidresin composition in an amount of less than 95 parts per hundred resin(phr).
 7. The composition of claim 1, wherein said first and said secondpoly(vinyl acetal) resins each comprise at least 50 weight percent ofresidues of n-butyraldehyde, based on the total weight of aldehyderesidues of said first or said second poly(vinyl acetal) resin.
 8. Aninterlayer comprising a resin layer that includes said resin compositionof claim 1.